1. Field of the Invention
The present invention relates to electronic apparatuses for connection with an external electric device, and particularly to photoelectric conversion modules for connecting an opto-electric hybrid cable (containing an optical fiber and an electric wire) to an external electric device.
2. Description of Related Art
In order to handle growing amount of information resulting from the rapid proliferation of the Internet and multimedia applications, optical interconnection technologies are being developed for use in optical signal transmission between various processing devices. In conventional photoelectric conversion modules, for example, an array of optical elements is disposed at the front end of a connector and is connected with an optical fiber, and the optical elements convert optical signal from the fiber into electrical signal (e.g., JP-A-2003-149512). In most electronic devices, a demand exists for reduced size and improved heat dissipation capability. For example, JP-A-2006-245025 discloses a structure for dissipating heat generated from components in an electronic device casing, in which the heat generating components are thermally coupled with a heat dissipation plate (having integrated thereon circuit components), and the heat dissipation plate is exposed to the exterior of the casing.
In addition to such optical interconnection, electrical connections (low-speed signal, power supply, grounding, etc.) are also required. For this purpose, opto-electric hybrid cables containing both an electric wire and an optical fiber are often used.
FIG. 3 is a schematic illustration showing a plan view of a conventional photoelectric conversion module for connecting an opto-electric hybrid cable to an external electric device. As shown in FIG. 3, in the conventional photoelectric conversion module 31, an electrical wiring circuit and an optical element 33 are provided on the surface of a glass epoxy substrate 32. An optical fiber 34 of an opto-electric hybrid cable 38 is disposed to face the optical element 33, while an electric wire 35 of the opto-electric cable 38 is connected to an input terminal Pi of the electrical wiring circuit. Further, a connector 37 is electrically connected to output terminals Po of the substrate 32 via cables 36.
The optical element 33 (or the optical element 33 and a controller IC for controlling the optical element 33) converts optical signal from the optical fiber 34 to electrical signal, which is then outputted to the connector 37 via the cable 36 connected to the output terminal Po. Likewise, electrical signal is inputted from the electric wire 35 to the input terminal Pi, and is outputted to the connector 37 via the cable 36 connected to the output terminal Po. By connecting the connector 37 of the photoelectric conversion module 31 to an external electrical device, the opto-electric hybrid cable 38 can be connected to the external electrical device. Although, for simple explanation, FIG. 3 illustrates a photoelectric conversion module containing only one optical fiber 34 and only one electric wire 35, a photoelectric conversion module containing multiple optical fibers 34 and multiple electric wires 35 can be similarly configured.
Typically, in the photoelectric conversion module 31, the glass epoxy substrate 32 and the connector 37 are integrated, and in order to form a protective cover for the optical fiber 34 and the optical element 33, a resin is molded over a region extending from a back side portion of the connector 37 to a front end portion of the opto-electric hybrid cable 38.
A problem with such a conventional photoelectric conversion module 31 is that the resin used for molding the protective cover may cause faults such as breakage of the cable 36 due to stresses exerted thereon and as bending of the terminals of the connector 37. Another problem is that such a protective resin cover provided over the entire photoelectric conversion module 31 may inhibit efficient dissipation of heat generated from components such as optical elements and ICs.